RF pulse reflection reduction for processing substrates

Abstract

Methods and systems for RF pulse reflection reduction in process chambers are provided herein. In some embodiments, a method includes (a) providing a plurality of pulsed RF power waveforms from a plurality of RF generators during a first time period, (b) determining an initial reflected power profile for each of the plurality of pulsed RF power waveforms, (c) for each of the plurality of pulsed RF power waveforms, determining a highest level of reflected power, and controlling at least one of a match network or the RF generator to reduce the highest level of reflected power, (d) determining an adjusted reflected power profile for each of the plurality of pulsed RF power waveforms and (e) repeating (c) and (d) until the adjusted reflected power profile for each of the plurality of pulsed RF power waveforms is within a threshold tuning range.

The invention claimed is: 
     
       1. A method comprising:
 (a) providing a plurality of pulsed RF power waveforms from a plurality of RF generators to a process chamber during a first time period; 
 (b) determining an initial reflected power profile for each of the plurality of pulsed RF power waveforms; 
 (c) for each of the plurality of pulsed RF power waveforms,
 determining a highest level of reflected power during the first time period, and 
 controlling at least one of a match network coupled to an RF generator that produced the pulsed RF power waveform, or the RF generator that produced the pulsed RF power waveform, to reduce the highest level of reflected power; 
 
 (d) determining an adjusted reflected power profile for each of the plurality of pulsed RF power waveforms; and 
 (e) repeating (c) and (d) until the adjusted reflected power profile for each of the plurality of pulsed RF power waveforms is within a threshold tuning range. 
 
     
     
       2. The method of  claim 1 , wherein each initial reflected power profile includes a plurality of different levels of reflected power during the first time period. 
     
     
       3. The method of  claim 1 , wherein the reflected power profiles for each of the plurality of pulsed RF power waveforms is affected by all the pulsed RF power waveforms provided to the process chamber at any given time. 
     
     
       4. The method of  claim 1 , wherein a first pulsed RF power waveform of the plurality of pulsed RF power waveforms is an RF source signal. 
     
     
       5. The method of  claim 4 , wherein a second pulsed RF power waveform of the plurality of pulsed RF power waveforms is an RF bias signal. 
     
     
       6. The method of  claim 1 , wherein the initial reflected power profile and the adjusted reflected power profile are measured reflected power values. 
     
     
       7. The method of  claim 1 , wherein a frequency of each of the plurality of pulsed RF power waveforms is different from each other. 
     
     
       8. The method of  claim 1 , wherein each of the plurality of pulsed RF power waveforms are synchronized. 
     
     
       9. The method of  claim 1 , wherein the match network coupled to the RF generator that produced the pulsed RF power waveform is controlled to reduce the highest level of reflected power. 
     
     
       10. The method of  claim 9 , wherein the match network includes a variable capacitor, and wherein the variable capacitor is electronically or mechanically tuned to reduce the highest level of reflected power. 
     
     
       11. The method of  claim 1 , wherein the RF generator that produced the pulsed RF power waveform is controlled to adjust a frequency of the pulsed RF power waveform to reduce the highest level of reflected power. 
     
     
       12. The method of  claim 1 , wherein the threshold tuning range is a range between a highest reflected power for a RF power waveform and a lowest reflected power for a RF power waveform. 
     
     
       13. The method of  claim 1 , wherein the threshold tuning range is a predefined value. 
     
     
       14. The method of  claim 1 , wherein the threshold tuning range applied to each of the plurality of RF power waveforms is the same range. 
     
     
       15. A non-transitory computer readable medium having instructions stored thereon that, when executed, cause a method of RF pulse reflection reduction in a process chamber to be performed, the method comprising:
 (a) providing a plurality of pulsed RF power waveforms from a plurality of RF generators to a process chamber during a first time period; 
 (b) determining an initial reflected power profile for each of the plurality of pulsed RF power waveforms; 
 (c) for each of the plurality of pulsed RF power waveforms,
 determining a highest level of reflected power during the first time period, and 
 controlling at least one of a match network coupled to an RF generator that produced the pulsed RF power waveform, or the RF generator that produced the pulsed RF power waveform, to reduce the highest level of reflected power; 
 
 (d) determining an adjusted reflected power profile for each of the plurality of pulsed RF power waveforms; and 
 (e) repeating (c) and (d) until the adjusted reflected power profile for each of the plurality of pulsed RF power waveforms is within a threshold tuning range. 
 
     
     
       16. The non-transitory computer readable medium of  claim 15 , wherein the match network coupled to the RF generator that produced the pulsed RF power waveform is controlled to reduce the highest level of reflected power. 
     
     
       17. The non-transitory computer readable medium of  claim 15 , wherein the match network includes a variable capacitor, and wherein the variable capacitor is electronically or mechanically tuned to reduce the highest level of reflected power. 
     
     
       18. The non-transitory computer readable medium of  claim 15 , wherein the RF generator that produced the pulsed RF power waveform is controlled to adjust a frequency of the pulsed RF power waveform to reduce the highest level of reflected power. 
     
     
       19. A substrate processing system comprising:
 a plurality of RF generators configured to provide a plurality of pulsed RF power waveforms to a process chamber during a first time period; 
 a plurality of sensors configured to measure reflected power for the plurality of pulsed RF power waveforms; and 
 a plurality of match networks each coupled to one of the plurality of RF generators, wherein each of the plurality of match networks is configured to:
 (a) determine a reflected power profile for one of the plurality of pulsed RF power waveforms based on measurements from one of the plurality of sensors; 
 (b) determine a highest level of reflected power of the reflected power profile during the first time period; 
 (c) reduce the highest level of reflected power; 
 (d) determine an adjusted reflected power profile for each of the plurality of pulsed RF power waveforms based on a second set of measurements from one of the plurality of sensors; and 
 (e) repeating (b) and (d) until the adjusted reflected power profile for each of the plurality of pulsed RF power waveforms is within a threshold tuning range. 
 
 
     
     
       20. The substrate processing system of  claim 19 , wherein each reflected power profile includes a plurality of different levels of reflected power during the first time period.